Introduction to Chest Radiography

Transcription

1 Introduction to Chest Radiography RSTH 366: DIAGNOSTIC TECHNIQUES Alan Alipoon BS, RCP, RRT Instructor Department of Cardiopulmonary Sciences 1

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3 Introduction Discovered in 1895 by Wilhelm Roentgen Terminology 1) X-Rays Roentgenograms Radiograph 3

4 Radiation Physics Electromagnetic waves 4

5 Radiation Physics (page188 text) Cathode produces electrons which impact tungstenanode to produce x-rays 5

6 Radiation Physics

7 Radiation Physics High energy waves have penetrating power Degree of penetration recorded as shadows on image receptor (X-ray film) 7

8 Radiation Physics X-rays are not reflected back like light rays but penetrate matter Their ability to penetrate is dependent of the density of matter Dense objects such bone absorb more x- rays (allow less penetration) Low-density objects such as air filled objects allow x-rays to pass through easily Radiographic densities 8

9 Radiographic Densities Radiation Physics *increase density = lighter (white) film shadow (radiopaque) *decrease density = darker film shadow (radiolucent) 9

10 Radiation Physics Four classifications of radiographic densities 1) Bone, very dense 2) Water, less dense 3) Fat, mildly radiolucent 4) Air, very radiolucent 10

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13 Pulmonary Edema- Pre and Post Diuresis

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15 Densities 15

16 Radiation Physics Distance between the source of x-ray and object The closer the object is to the source the greater the magnification and distortion of the object The further the object is to the source the smaller and sharper the object For a PA chest x-ray the patient and film are positioned approximately 6 feet from the x-ray source A portable chest x-ray the patient and film are positioned approximately 4 feet from the x-ray source 16

17 Radiation Physics

18 Value of the Chest X-ray Relevancy to Respiratory Therapy Diagnosis of lung disease Help determine appropriate and effective therapy (pneumothorax) Evaluate the effectiveness of treatment Determine position of endotracheal tubes Provide dynamic portrait of the progression of the disease process (serial films) Identify complications 18

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24 Chest X-ray Usage Stable patient with undiagnosed respiratory problems Routine chest x-ray important for patients over the age of 40, especially in smokers Evaluate changes in lung pathology a. effects of treatment (ex. IPPB with atelectasis, lung recruitment maneuvers) b. acute problems may require frequent chest x-rays while chronic changes require less frequent films 24

25 Clinical Indications For Chest Radiograph See Box 10-1 page

26 Chest X-ray Usage, cont. Do not withhold oxygen or mechanical ventilation to get a chest X-ray in acutely ill 26

27 Limitations 1.May be normal with significant lung disease (ex. asthma, chronic bronchitis) 2.Abnormalities in "blind" areas may not be detected 3.X-ray may be clinically behind pathology (ex. pneumonia and ARDS) 4.Chest X-ray may be normal in patients with respiratory insufficiency from extrapulmonary abnormalities 27

28 Views (Positions) 1.Magnification and sharpness depend on distance between X-ray source and chest - closer source is to chest, greater magnification and less focused (and vice versa) 28

29 Views (Positions) 2. Exposure regulated by technician 3. Standard chest radiographs at full inspiration. 29

30 Views (Positions) Posteroanterior (PA) view Anteroposterior (AP) view Left lateral view Lateral decubitus view Lordotic view Oblique view End expiratory film

31 Standard view Posteroanterior (PA) view Film against anterior chest. X-ray travels through posterior chest to anterior chest to expose film 31

32 Posteroanterior (PA) view

33 Posteroanterior (PA) view 33

34 Posteroanterior (PA) view 34

35 Heart chambers PA view

36 Posteroanterior (PA) view Advantages a) decreased magnification and increased sharpness b) rotate scapulae out of way c) easily identified air/fluid levels d) anatomical reality 36

37 Posteroanterior (PA) view Disadvantages?

38 Anteroposterior (AP) View 1. Portable CXR 2. Film against posterior chest X-rays pass through anterior to posterior to expose film 38

39 Anteroposterior (AP) View

40 Anteroposterior (AP) View 40

41 AP PA 41

42 Anteroposterior (AP) View Advantages a) portability b) viewing posterior chest abnormalities 42

43 Anteroposterior (AP) View Disadvantages a) heart shadow magnified b) asymmetric radiograph c) decreased sharpness d) poor inspiratory effort e) artifactual shadows present 43

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46 AP views PA 46

47 Left Lateral View Left lateral most common Film against lateral chest, X-rays pass through right and then left side of chest to expose film 47

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49 Left Lateral View 49

50 Heart chambers- Lateral view

51 Left Lateral View Advantages a) heart magnification decreased b) can see behind heart and diaphragms c) 3D view d) can view left lung better than with PA view 51

52 Lateral Decubitus View Left or right 2. Patient on affected side 3. Film against posterior chest. Patient lies on right/left side with X-rays passing through chest in AP manner to expose film 4. Advantage - show free fluid (pleural or parenchymal) 52

53 Lateral Decubitus View 53

54 PA/Lateral view of a patient with a large right pleural effusion 54

55 Right lateral decubitus (right side down) view of the same patient, showing layering of the large effusion along the right chest wall. 55

56 Lordotic View Film against posterior chest. X-rays pass upward at approximately 45 o angle A to P from a lower position to expose film 56

57 Lordotic View Advantages a) clearer (bone-free) view of upper lobes b) separation of superimposed densities 57

58 Lordotic 58

59 Lordotic 59

60 Oblique View Right or left Film against anterior or posterior chest. Patient is rotated right (45 0 ) or left and X-rays pass P to A or A to P to expose film 60

61 Oblique View Advantage - reduces superimposed images 61

62 End-expiratory film Taken at end-exhalation Advantages a) evaluate diaphragm excursion b) aid pneumothorax detection 62

63 Inspiration:Expiration CXR 63

64 Postprocedural Chest X-Ray Evaluation Tracheal Intubations Central Venous Pressure Line Pulmonary Artery Catheter Placement Nasogastric Feeding Tubes Chest Tubes

65 Tomography 1. Simultaneous movement of film and X-ray source around a specific axis. 2. Allows selective visualization of specific area. 3. Used to evaluate mediastinal or parenchymal areas *C.A.T. (Computerized Axial Tomography) ("Cat Scan") - computer processing of X-ray which gives cross-sectional image 65

66 Tomography is the process of generating a two-dimensional image of a slice or section through a 3- dementional object (a tomogram) 66

67 Tomography 67

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69 CT of the lungs, window level set to demonstrate the vessels and air ways - not intended to demonstrate the heart, spine muscles etc. This is used to look for things like pneumonia or lung cancer

70 Chest Tomography 70

71 Computed Tomography CT scanning Computed enhancement of x-ray shadows Results in an amazing clear look at internal anatomy Clarity of image is indispensable Cost 71

72 Computed Tomography CT scanning is extremely useful in the following areas (page 194 text) Lung tumors Chronic interstitial lung disease Acquired Immune Deficiency Syndrome (AIDS) Occupational lung disease Pneumonia Bronchiectasis Chronic Obstructive Pulmonary Disease 72

73 Bronchography 1. Instillation of radiopaque material (fluid) into tracheobronchial tree with subsequent radiographic analysis (Bronchogram) 2. Used to Diagnose - Carcinoma (Bronchogenic) - Tracheobronchial lesions - Congenital abnormalities - Airway deterioration 73

74 Bronchography 74

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76 Ventilation/Perfusion scans (V/Q scans) 1. Inhalation and/or injection of radioactive tracer into airways and/or pulmonary vasculature 2. Chest scanned with defects in ventilation or perfusion assessed 76

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78 Ventilation/Perfusion scans (V/Q scans) Abnormalities Decreased ventilation such as that caused by: - airway occlusion - bronchospasm - loss of elasticity - alveolar consolidation - airway compression 78

79 Ventilation/Perfusion scans (V/Q scans) Abnormalities decreased perfusion such as that caused by: - pulmonary emboli - loss of vascular bed - vascular compression 79

80 Magnetic Resonance Imaging (MRI) 1. Principle - measurement of resonant protons present in tissue 2. Related to water and lipid content 3. Signal intensity proportional to fluid content, therefore, fluid appears white and air and cortical bone black 80

81 Magnetic Resonance Imaging (MRI) Advantages a) contrast resolution greater than CT b) can be used to measure fluid flow c) can be obtained in any plane d) tissue-specific diagnosis possible 81

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83 Lateral MRI 1.Left ventricle 2.Aorta 3.Pulmonary trunk 4.Left atrium 5.Breast 6.Spinal column 7.Serous pericardium (light green) 8.Fibrous pericardium (dark green) 83

84 Magnetic Resonance Imaging (MRI) 84

85 Magnetic Resonance Imaging (MRI) Disadvantages a) cost b) size c) motion artifact d) magnetic field 85